Orthogonal Frequency Division Multiple Access (OFDMA) technology can efficiently support multiple mobile stations with limited bandwidth and easily provide various Quality of Service (QoS). The OFDMA technology is a multiple access version of orthogonal frequency-division multiplexing (OFDM). OFDM is a modulation technique for data transmission based on frequency-division multiplexing (FDM), which uses different frequency channels to transmit multiple streams of data. In OFDM systems, a wide channel is divided into multiple narrow-band subcarriers, which allow orthogonal modulated streams of data to be transmitted in parallel on the subcarriers.
In OFDMA systems, the channel resource is divided into multiple time domain OFDMA symbols, with each OFDMA symbol partitioned into multiple narrow-band subcarriers. A base station (BS) allocates a subset of subcarriers in selected OFDMA symbols to each mobile station (MS) based on appropriate scheduling algorithms, enabling multiple MSs to share the channel resource in both frequency and time domain.
Since MSs are typically implemented as portable devices running on batteries, one of the most critical considerations in MS design is power consumption. Although various power saving techniques have been developed for communication systems, there is a need for a method of reducing power consumption in a multi-user digital communication system and a mobile station employing the method.